A disk drive, such as a hard disk drive (HDD), comprises a magnetic disk, spindle motor, magnetic head, and carriage assembly. The magnetic disk is disposed in a case. The spindle motor supports and rotates the disk. The magnetic head reads and writes information to and from the disk. The carriage assembly supports the head for movement relative to the disk. The magnetic head comprises a slider mounted on a suspension of the carriage assembly and a head section. The head section comprises a recording head for writing and a reproducing head for reading.
In recent years, a magnetic head for perpendicular magnetic recording has been proposed to increase the recording density and capacity or reduce the size of a magnetic disk drive. In the magnetic head of this type, a recording head comprises a main pole, write/shield pole, and coil. The main pole produces a perpendicular magnetic field. The write/shield pole is located on the trailing side of the main pole with a write gap between the poles and closes a magnetic path between itself and a magnetic disk. The coil serves to pass a magnetic flux through the main pole. Side shields that are magnetically coupled to the write/shield pole are arranged individually on the opposite sides of the main pole transversely relative to the tracks. An end portion of the main pole is partially located between the side shields (e.g., Jpn. Pat. Appln. KOKAI Publications Nos. 2009-4089 and 2007-294059).
A recording magnetic field is applied to the magnetic disk from just below the main pole, whereupon record patterns are perpendicularly recorded along tracks that are almost as wide as the write gap.